1. Field of the Invention
This invention relates generally to metal beams used in a grid structure for a suspended ceiling, and more particularly, to a connection that joins together, end-to-end, main beams in the grid.
2. Background Art
Suspended ceilings having metal beams called tees, or runners, that form grids to support panels, are well known. Such grids have main beams and intersecting cross beams. The beams are formed generally of flat sheet metal folded into an inverted T-shape, but in some instances are extruded metal, such as aluminum. The main beams are connected end-to-end and are suspended from a structural ceiling by wires. The cross beams are connected end-to-end through slots in the main beams and are supported by such main beams.
The main beams, which run parallel to one another, are generally spaced 48xe2x80x3 apart. Cross beams are connected to the main beams to form either 24xe2x80x3xc3x9724xe2x80x3 square openings, or 24xe2x80x3xc3x9748xe2x80x3 rectangular openings, which receive the laid-in panels.
Such main beams in a suspended ceiling are subjected primarily to tension, compression, and bending stresses, and occasionally to twisting forces. The function of the connection, which joins the generally 12 foot lengths of main beams together longitudinally, is to resist these stresses and forces, and to maintain adequate strength and alignment between the beams.
Any compression forces on.the connection exist longitudinally of the beams, which abut each other end-to-end, so that the connection has only to keep the ends of the beams aligned to resist these compressive forces. Fire relief notches are cut into the beam proper to provide for expansion relief from these compressive forces in case of fire, since there is no give at the beam end.
As to tension forces that pull apart one beam from another longitudinally, the connection is the sole means to resist such tension forces. With respect to bending, the connection, along with the beam-ends, must provide resistance to such bending. The connection must also resist the occasional twist.
Prior art connections on the ends of main beams were generally of two types.
In one type of connection, the connector elements were formed integrally with the beam itself; particularly out of the web portion of the beam. Such a construction caused loss of material from the cutting away to achieve the connecting elements. Furthermore, the process to make such connectors was a relatively slow one since, although the beam itself was made relatively rapidly in a roll forming operation, the connector itself was formed in one or more braking operations that generally required intricate forming of the relatively soft grid tee metal. Additionally, the soft metal of the tee had relatively little spring qualities that could be used to form the connection.
In another form of main beam, or tee, connection, clips alone are used to form the connection. A separate clip is attached to the end of each tee, which is squarely cut at the end. A clip is inset into a pan depressed in the tee, so that the clips can engage solely with one another, independent of the tee, along the central plane of the web. Clips permit the use of harder, springier steel than web metal where the connection is formed from the tee.
The connection of the present invention combines a pair of clips, as well as a pair of configured grid tees, to form a connection. Each of the clips fastened on a beam end is identical to the other clip in the pair, as is the grid tee construction at each of the beam ends identical to the construction on the other beam end in the pair.
A clip has holes for attachment to a beam web and has spring tabs that act to ramp the end of an opposing clip over a web during engagement, and then contract under pressure from the engaged connectors.
The beam itself has an end configuration essentially square but with a web cutout that eliminates interference with any stitches in the web and that also guides a clip while being engaged to form a connection. A spring pocket formed in the web of the beam, and an opening formed by the spring pocket, along with positioning bosses formed in the web, cooperate to permit a clip and beam end on one beam to engage and lock with a clip and end on an adjacent beam.
The clips themselves have elements, which cooperate with the integral beam elements, and the opposing clips, to form the connection.
The connection can be disengaged by, for instance, deforming the pockets to an open position and then separating beams sideways. The connection can be reengaged for reuse by simply restoring the pockets to their original closed position, and bringing the connectors together. When connected, the clips straddle the abutting webs with a clip on each side of the aligned webs.
In summary, the present invention combines a clip on a configured beam end, with the configured beam end itself, to form a main beam end-to-end connection with another combination of clip and configured beam end.